Electrical switch actuated by a reciprocated shaft with free end which passes through and beyond the switch into work contacting position to impart motion to other mechanism



y 1965 J. F. SHERWOOD 3,194,911

ELECTRICAL SWITCH ACTUATED BY A RECIPROCATED SHAFT WITH FREE END WHICH PASSES THROUGH AND BEYOND THE SWITCH INTO WORK CONTACTING POSITION TO IMPART MOTION TO OTHER MECHANISM Filed Oct. 7, 1965 John E Sherwood 7:. Rosy/ 7W ATTORNEY United States Patent ELECTRICAL SWITCH ACTUATED BY A RECIIRO- CATED SHAFT WITH FREE END WHICH PASSES THROUGH AND BEYOND THE SWITCH INTO WORK CONTACTING POSITION TO IMPART MOTION TO OTHER MECHANISM John F. Sherwood, 7801 W. 39th Ave, Wheat Ridge, Colo. Filed Oct. 7, 1963, Ser. No. 314,112 7 Claims. (Cl. 20tl67) This invention relates to an electrical switch adapted to be actuated by direct axial thrust of a reciprocated shaft which has a piston or force-receiving portion at one end and an opposite free end which contacts other mechanism at the limit of the work stroke of the shaft for the purpose of transmitting motion to such other mechanism. An example of such a shaft is the type used in small thermal actuators wherein the piston portion of the shaft is embedded in expansible and contractible material encased in a high pressure housing, and the free end of the shaft projects axially beyond the housing for contact with the mechanism to be actuated by the shaft.

Heretofore electrical switches have been located laterally of the reciprocated shafts of such thermal actuators and have been operated by projections or other deformations on the side surfaces of the shaft. Such lateral location of the switches has necessitated use of relatively large housings or of uncommonly small switches, both of which result in increased cost and other objections.

The main object of this invention is to provide a switch located in axial alignment with the shaft which is intended to actuate the switch, and so constructed that reciprocation of the shaft in axial direction exerts a direct axial thrust on the switch mechanism.

Another object of the invention is to provide a switch mechanism located in axial alignment with the shaft and designed to be actuated by means located on a reciprocated shaft between the ends of the shaft, whereby the shaft can actuate other mechanism for the purpose of imparting motion thereto and also actuate the switch mechanism.

Another object of the invention is to provide a novel switch construction wherein the actuating thrust exerted by the shaft is not confined to the contact points of the switch. My switch mechanism includes a floating disc concentric with the switch actuating shaft, centrally apertured to slidingly receive the shaft for movement in axial direction through the floating disc. Contact between a flanged portion of the shaft and said floating disc, when the shaft is moved in axial direction and has reached the end of its work stroke, exerts uniform pressure against the disc, thereby moving the disc from the switch base toward a flexible blade on which is mounted the movable contact point. This action opens the switch at a predetermined time related to the shaft movement. The construction is such that the switch actuation is positive and not dependent on fine adjustment between the switch actuating means and the movable contact.

, These and other objects and advantages will be apparent from the drawings and following specification.

In the drawings:

FIG. 1 is a top plan view of an electrical switch embodying my invention.

FIG. 2 is a sectional view of the switch in the plane of the line 22 of FIG. 1, showing the contacts in closed position, and showing in elevation a shaft adapted to actuate the switch.

FIG. 3 is a view similar to FIG. 2, showing the contacts in open position, and a part of the shaft in elevation in its switch actuating position.

FIG. 4 is an exploded view of the switch parts, and of the shaft,in perspective.

3,194,911 Patented July 13, 1965 In the preferred embodiment of my invention shown in the drawings, a flat bottom switch base 10 of insulating material is provided with a central uniform diameter opening 11 and peripheral recesses 12, 13 and 14. Said recess 14 accommodates the electrical wiring (notshown) leading to the fixed and movable contacts. The recesses 12 and 13 accommodate switch base mounting screws (not shown). The base 10 is thickened by a blade-supporting portion 15 located on the top surface of the base adjacent one side of the base periphery. Concentric with the central opening 11 is a recess 16 best shown in FIG. 4.

A fixed contact support 17 with contact point 18 thereon is fastened to the base by prongs 19. The end opposite the point 18 is. provided with a hole 2th for attachment of the electrical wiring (not shown). A movable contact blade 21 is fastened by rivets 22 to the blade supporting portion 15 of the base. The blade 21 comprises a pair of parallel spring metal arms 23 connected together at one end by the apertured curved cross member 24 with apertured extension 24', and at the opposite end by the converging portions 25 of the arms 23 carrying the depending contact point 26 at their junction. Extending inwardly from the junction of the parts 25, is a curved leaf spring 27. The blade 21 is mounted on the base portion 15 in such position that the contact 26 registers with the fixed contact 18.

Between the base It) and blade 21, above the recess 16, is a floating disc 28 of insulating material, cut away at one side as indicated at 29. The disc is provided with a central aperture 30 smaller in diameter than the opening 11 in the base and concentric with said opening. The floating disc 28 has a depending flange 31 on its peripheral bottom edge for seating in the recess 16. The central hole 30 communicates with a slot 32 extending to the cut away side edge 29. A rib 33 extends diametrically across the top of the floating disc 28.

A retainer car 34 comprises a flat apertured base 35 and upturned ear 36 provided with a groove 37 which extends across the face of the ear for reception of the end of the leaf spring 27 of the movable cont-act blade 21. The base 35 of the car 34 is fastened to the base 10 by a rivet 38.

An upper stop 49 comprises a base 41 with prongs 42 for fastening the stop on the base 10 in such position that the flat top member 43 overlies the arms 25 above the :movable contact 26.

When the described parts are mounted on the base 10, the floating discj28 rests loosely on the base, with the flange .31 in the base recess .16, and the apertures 11 and 30 registering concentrically. Due to the smaller diameter of the aperture 30 in the floating disc, a shaft bearing surface 45 is formed on the under side of the floating disc surrounding the hole 30 for a purpose to be explained.

To illustrate the operation of the switch, I have shown one form of a reciprocated shaft suitable for actuating the switch. The shaft 50 comprises a force receiving or piston end portion :51 and a free end 52 on which is mounted a cap 53 provided with a flange 54 on its inner end. The diameter of the capped end 5253 is such that the shaft can move freely through the opening 11 of the base and slidably through the aperture 30 of the floating disc 28. The diameter of the flange 54 on the shaft is such that it can move slidably into the opening 11 of the base but abuts the shoulder 45 surrounding the opening 30 in the floating disc 28 when the shaft has been moved a predetermined distance outwardly on its power stroke. The shaft illustrated is suitable for having its piston end 51 embedded in thermally expansible and contractible material encased in a high pressure casing, expansion causing the shaft to move outwardly relatively to the casing so that the free end 53 can contact other mechanism,

J9 such for example as a valve or dam-per, to impart motion to such other mechanism. Thus the end 53 is free to perform its int-ended function and at the same time the shaft, by virtue of the flange 54 located between the shaft ends, exerts direct axial thrust on the switch mechanism to open the contacts 1846.

The operation of the switch mechanism is as follows: When the shaft 50 is in its retracted position as shown in FIG. 2, the switch parts appear as shown, with contacts 18-26 closed, and the shaft extending loosely through the central opening ll in the base it) and slidably through the hole 36 in the floating disc 23. When the shaft St} or other suitable actuating member is advanced by movement through the switch so that the flange 54 or other deformation of the shaft contacts the bearing surface on the under side of the floating disc 28, said disc is moved in axial direction out of its recess 16 in the base toward the spring metal blade 21. When the floating disc presses against the blade 21 the arms 23 bend slightly and raise the converging arms 25 to lift the contact point 26 away from the fixed contact 18 into the open switch position shown in FIG. 3.

When the movable contact 26 snaps away from the stationary contact 18, the stop member 49 limits the movement of the blade 21 and contact 26. The stop member 4t has an aperture 44 to which wiring leading to another contact (not shown) may be connected.

When the floating disc 28 is contacted by the flange 54 of the shaft 59, it exerts uniform pressure on the arms 23 of the flexible blade 21 through the rib 33 on the upper surface of the floating disc 28, thereby positively opening the switch and cutting off current to the means which actuate the shaft. In a thermal motor, this action allows the thermally responsive material to cool and contract, ermitting the shaft to return to original posit-ion either by pressure of the work on the shaft end or by external means such as a spring for moving the shaft to original position. The return movement of the shaft permits the contact 26 to snap back to the FIG. 2 position, causing the circuit to close again.

The provision of the relatively large bearing surface 55 on the under side of the floating disc 28 surrounding the opening 30, designed for receiving the thrust exerted by the flanged shaft St or other suitable means, is an important feature of my switch construction. It obviates any possibility of the switch being bypassed as is possible when a switch is located laterally of a shaft and actual contact between the actuating means and the switch mechanism is limited to the movable point, and requires precision fit of parts for dependable operation.

Another valuable advantage of my invention is the fact that the switch actuating shaft can perform its work function by exerting pressure through its free end against mechanism located externally of the switch housing, and also simultaneously actuate the switch to control the stroke of the shaft. While it is possible to have direct contact by the head of a shaft against a switch, the disadvantage is that the unit would have to be enlarged to accommodate the full shaft stroke, but in such case the shaft could not perform work directed to pushing external mechanism.

Further, the mounting of my switch in a housing is extremely simple. It may be dropped into a housing to surround a shaft end and then be screwed in place. No springs or other adjustments are necessary. T he switch parts are so mounted on their base that a work shaft can pass all the switch mechanism concentrically and complete its work stroke before contacting the floating disc for actuating the movable contact point and opening the circuit.

Changes may be made in details of construction and form of certain parts without departing from the scope of the invention as defined in the following claims.

I claim:

ll. In combination with a reciprocated actuator shaft which has means between its ends for actuating a switch and which has a free end which passes through the switch into work contacting position for imparting motion to other mechanism, an electrical switch comprising (a) a base of insulating material having an opening extending therethrough,

(b) a fixed contact point on one face of the base,

(0) a floating disc loosely supported on said face, said disc having an aperture therethrough smaller in diameter than the opening in the base,

(d) a flexible blade free at one end and mounted at its other end on the base to overlie the floating disc, said blade having an opening therein at least as large as the aperture in the disc, and

(e) a movable contact point on the free end of the blade for engagement with the fixed contact point,

(f) said base opening, floating disc aperture and blade opening being axially aligned to receive the reciprocated shaft therethrough, and the floating disc receiving bearing pressure in an annular area surrounding its aperture from the switch actuating means on the shaft, whereby the floating disc moves bodily and transmits pressure against the flexible blade and separates the contact points on the base and blade when the shaft has moved in axial direction into work contacting position.

2. The electrical switch defined by claim 1, in which the base is provided with an annular recess on one face concentric with the base opening, and the floating disc has a depending peripheral flange adapted to seat in said recess.

3. The electrical switch defined by claim 1, in which the flexible blade comprises a pair of laterally spaced apart spring metal arms, a cross member connecting the arms together at one end, means connecting said cross member to the base, and converging extensions on the opposite ends of the arms forming a junction on which said movable contact is mounted.

4. The electrical switch defined by claim 3, which includes a blade retaining ear mounted on the base, and a leaf spring extending from the converging extensions of the blade to the retaining ear for urging the blade and movable contact point into contact point closing position.

5. The electrical switch defined by claim 3, in which the floating disc has a rib extending diametrically across one surface for hearing against the spring metal arms of the blade when pressure is exerted on the opposite side of the floating disc.

6. The electrical switch defined by claim 1 in which the base is provided with a thickened portion adjacent one peripheral side edge, and said flexible blade is mounted on said thickened portion in spaced overlying relation to the floating disc.

7. In combination with a reciprocated actuator shaft which has means between its ends for actuating a switch and which has a free end which passes through the switch into work contacting position for imparting motion to other mechanism, an electrical switch comprising (a) a base of insulating material having an opening extending therethrough,

(b) a fixed contact point on one face of the base,

(c) a floating disc loosely supported on said face, said disc having an aperture therethrough smaller in diameter than the opening in the base,

(d) a flexible blade free at one end and mounted at its other end on the base to overlie the floating disc, said blade having an opening therein at least as large as the aperture in the disc, and

(e) a movable contact point on the free end of the blade for engagement with the fixed contact point,

(f) a leaf spring on the flexible blade extending inwardly from the movable contact into the blad aperture, i

(g) a blade retaining ear mounted on the base and having a groove extending across the ear for reception of the leaf spring, and

(h) a stop member mounted on the base overlying the movable contact for limiting movement of the blade and contact;

(i) said base opening, floating disc aperture and blade opening being axially aligned to receive the reciprocated shaft therethrough, and the floating disc receiving bearing pressure in an annular area surrounding its aperture from the switch actuating means on 10 the shaft, whereby the floating disc moves bodily and transmits pressure against the flexible blade and separates the contact points on the base and biacle When the shaft has moved in axial direction into Work contacting position.

Reterences Cited by the Examiner UNITED STATES PATENTS 2,502,326 3/50 Koonz et al.

BERNARD A. GILHEANY, Primary Examiner.

ROBERT K. SCI-IAEFER, Examiner. 

1. IN COMBINATION WITH A RECIPROCATED ACTUATOR SHAFT WHICH HAS MEANS BETWEEN ITS ENDS FOR ACTUATING A SWITCH AND WHICH HAS A FREE END WHICH PASSES THROUGH THE SWITCH INTO WORK CONTACTING POSITION FOR IMPARTING MOTION TO OTHER MECHANISM, AN ELECTRICAL SWITCH COMPRISING (A) A BASE OF INSULATING MATERIAL HAVING AN OPENING EXTENDING THERETHROUGH, (B) A FIXED CONTACT POINT ON ONE FACE OF THE BASE, (C) A FLOATING DISC LOOSELY SUPPORTED ON SAID FACE, SAID DISC HAVING AN APERTURE THERETHROUGH SMALLER IN DIAMETER THAN THE OPENING IN THE BASE, (D) A FLEXIBLE BLADE FREE AT ONE END AND MOUNTED AT ITS OTHER END ON THE BASE TO OVERLIE THE FLOATING DISC, SAID BLADE HAVING AN OPENING THEREIN AT LEAST AS LARGE AS THE APERTURE IN THE DISC, AND (E) A MOVABLE CONTACT POINT ON THE FREE END OF THE BLADE FOR ENGAGEMENT WITH THE FIXED CONTACT POINT (F) SAID BASE OPENING, FLOATING DISC APERTURE AND BLADE OPENING BEING AXIALLY ALIGNED TO RECEIVE THE RECIPROCATED SHAFT THERETHROUGH, AND THE FLOATING DISC RECEIVING BEARING PRESSURE IN AN ANNULAR AREA SURROUNDING ITS APERTURE FROM THE SWITCH ACTUATING MEANS ON THE SHAFT, WHEREBY THE FLOATING DISC MOVES BODILY AND TRANSMITS PRESSURE AGAINST THE FLEXIBLE BLADE AND SEPARATES THE CONTACT POINTS ON THE BASE AND BLADE WHEN THE SHAFT HAS MOVED IN AXIAL DIRECTION INTO WORK CONTACTING POSITION. 